Preparation Of Multicomponent Composites And Their Phosphorus Adsorption Properties

The excessive release of phosphorus（P）will cause water pollution and lake eutrophication,so it is more important to remove phosphorus effectively.In this paper,the metal material was prepared by the mature synthesis method of magnesium-aluminium dihydroxide.D331 resin was modified with the material as the matrix and used as the phosphorus removal adsorbent.Two lanthanide ternary metal composites were synthesized by coprecipitation method.They were used as new adsorbents to remove phosphorus-containing wastewater.Microstructure and morphology of the prepared materials were analyzed by means of SEM,XPS and FT-IR.The effects of adsorbent reaction time,solution pH value and reaction temperature on the adsorbent materials were studied,and the possible mechanism of phosphorus removal and adsorption was explored.（1）Magnesium-aluminiumdihydroxide（Mg-Al-LDH）waspreparedby coprecipitation method to modify D331 resin（macroporous acrylic acid weak base anion exchange resin）.As a kind of phosphorus adsorption material,the adsorption capacity of D331 resin modified by magnesium-aluminium dihydroxide was obviously enhanced.When the pH was below 5.71,the adsorption capacity of modified resin was strong,and the adsorption capacity of phosphate was gradually increased.The q_m of D331 resin was 42.51 mg/g.The phosphorus removal efficiency of modified D331 resin increased from 62.46%to 92.34%when the amount of modified resin increased from 0.07 g/L to 0.2 g/L.The thermodynamic parameter△H>0 is positive.The adsorbent belongs to endothermic reaction.The increase of temperature is beneficial to the modification of resin.The adsorption model conforms to the Franklich model.The adsorption reaction proceeded rapidly in the first 9 hours,and the adsorption capacity increased from 8.38 mg/g to 36.63 mg/g,an increase of337.1%.The adsorption kinetics can be described by the pseudo-second-order kinetics equation.The anions in the solution have some influence on the adsorption of the modified resin.The order of influence is CO₃^2->SO₄^2->NO₃^-.Through characterization analysis,the mechanism of phosphate adsorption by modified resin may be chemical adsorption between resin and phosphate,forming an inner complex.（2）By synthesizing lanthanide metal ferric-calcium-lanthanum ternary composite oxide adsorbent（FCL）with molar ratio of 1:1:1 of Fe,Ca and La,the effects of different pH value（acidity and basicity）,reaction time and temperature on phosphorus adsorption of the adsorbent were studied comprehensively.When the pH value increased,the amount of phosphorus adsorbed decreased significantly,the pH value was 3.02,and the q_m of adsorption was 30.16 mg/g.When the amount of FCL is 0.05g（i.e.0.1 g/L）,the phosphorus removal rate exceeds 95%.The coexistence anions in aqueous solution hindered the adsorption,and the relationship was CO₃^2->SO₄^2->Cl^->NO₃^-.Phosphate adsorption tends to equilibrium in 4 hours,and FCL adsorbent conforms to the pseudo-second-order model.Thermodynamic parameters show that△H is greater than zero,△G is negative,and the adsorption reaction is endothermic and spontaneous.The removal rate of FCL adsorbent was 73.32%after five cycles of adsorption,desorption and re-adsorption.According to FT-IR and XPS measurements,electrostatic attraction and external complexation are the main mechanisms of phosphorus adsorption by FCL.（3）Fe-Mn-La（FML）phosphate removal adsorbent was prepared by coprecipitation method.FML adsorbent was analyzed by X-ray diffraction and other analytical means.The effects of different factors on phosphate adsorption performance were investigated,and the possible mechanism of phosphate removal was explored.With the increase of pH value,the adsorption capacity of phosphate decreased.When the pH value was 3.02,the maximum adsorption capacity of FML to phosphate in the system was 45.96 mg/g.When the temperature is 318.15 k,the phosphate conforms to Langmuir model,and the maximum adsorption capacity q_m reaches 71.68 mg/g.In addition,the effect of anion CO₃^2-on phosphate adsorption is obvious.FML adsorbent regeneration cycle experiment showed that after five cycles,the adsorption capacity was still 78.30%of the original cycle.